speaker low end and room size : which ratio?

[Eldam]

thanks,

The speakers in a room is like a F1 on a circuit : it has to be set up and i understand it's no possible today without electronic (crossover, etc) especially between bass and the rest of the drivers.

Understand now it has to be tailor maid...because of the complexity of the room and the listener preferences.

In final i wanted to know where start the bass frequency which mask the rest of above audio range for clarity of the sound in a flat curve (in a specific area)!

Maybe i'm too theoric. Then I understand too that my ears have not the same sensibility at 80 db in the room than at 100 dB...the same for the room ! My hope was to have illusion of bass with impact without the bass mask everythings... because ESL planar (= need bass with a big control of the amps (don't find in the world internet someone who have satisfaction with a sub and Quad ESL63 for example), that's why my original question : there is a lot of life in the 80 to 100 - 150 hz... and we need to deal with it... above & below.

measurement & electronic (is there something for active crossover like DCX2496 or mini DSP but less pricy ? old lantop+software ?)

I planed Two way miniDSP because acceptable price but fear to need 3 way to go to magnetic planar if Two way ESL+ bass don't work...

Difficult, difficult !

 

[gedlee]

In final i wanted to know where start the bass frequency which mask the rest of above audio range for clarity of the sound in a flat curve (in a specific area)!

measurement & electronic (is there something for active crossover like DCX2496 or mini DSP but less pricy ? old lantop+software ?)

I don't know of any masking that takes place from low to high frequencies when the system is flat. In fact I would suspect the opposite due to lower loudness perception of lows versus highs. A few dB rise from mid to low is usually perceived to be neutral. If the lows are masking anything then it is because the level is too high.

I use a DCX2496 for bass management, it is ideal, but a MiniDSP can also work.

 

[aulday]

What you are seeing is very common. Smaller speakers if built right, generally do not have much bass. That is precisely why they don't throw Rock Concerts with 5" bookshelf speakers. But there is a trick the makers of bookshelf speakers use. To create the sense of bass, the create a bass bump in the Bass Presence range.

That is precisely the range you spoke of. I had some very low cost speaker, Sony 5" bookshelf with rated bass at 80hz, but they still sounded like they had very good bass. But perception is not reality. The sounded like they had good bass, but they didn't.

Now, the same trick can be applied to cheaper floorstanding speakers too. The put a big bass bump in, young men are impressed. They buy the speakers.

But, in better floorstanding, and bookshelf too, you don't want to be fooled, quite the opposite, you want reproduction as close as possible to what is contained on the Medium (vinyl records, CDs, etc...). Therefore these better speakers don't have over-amp, hyper, droning, exaggerated bass. But they sound stunning. And I have hear very very expensive very clear speaker that initially didn't seem to have any bass until I realized I could feel it slamming into my body. It was rendered perfectly, or as perfectly as $4000/pr speaker can.

There are other tricks as well. If you want to give the illusion of great life and presence to speaker, you simply build in an upper midrange bump.

But to a finely tuned ear, all these 'Tricks' get tiring after a while.

So, don't confuse perception with reality. It is easy to create perception in speaker, with out actually delivering on the thing that is perceived. Speaker like this get tiring over time, and when you get them home and live with them for a while ...very quickly... the thrill is gone.

Generally you do not design speaker to a room unless you know you are going to be in that room until you die. Room specific speaker work best in the room they are specific too.

However, if you want to anticipate trouble frequencies within a room, simply divide the room dimensions into the speed of sound. Using American units, let's say you have a room that is 18 feet long. The speed of sound in air is 1128 ft/s.

So -
F1 = S/y = 1128/18 = 62.7hz

This is the frequency that that dimension will resonate at.

Let's say the other dimension is 15 feet =

F2 = 1128/15 = 75.2 hz

And let's say you have 8 foot ceilings -

F3 = 1128/8 = 141 hz

Let's say you place you speaker 3 feet from the side wall, and 2 feet from the wall behind the speaker. We can find the frequencies associate with these distances.

F4 = 1128/3 = 376hz

F5 = 1128/2 = 564hz

So, we have these frequencies to consider.

As to mids and high, though it depends on the circumstance, generally, the more you amp up the bass, the muddier your midrange gets. For example, a speaker that sounds fine in the middle of the room, when pushed into the corner is likely to have great powerful bass, but the midrange is likely to be cloudy, muddled, and muddy.

So ...what to do...what to do?

Answer, design the speaker to a reasonable blend of your taste, a fair evaluation of your room acoustics, and to a fair standard of fidelity. Everything in life is a compromise. Just remember that life and speakers are like squeezing a balloon, you can get it down in one area, but it is going to blow up in another. Find the workable compromise.

Next, I'm not sure of the size of your room. You gave it in METERS, yet apologies for using inches. So, it that 20 to 30 Square Feet or 20 to 30 Square Meters?

25 Squares Meter would be 269 Square Feet, which would be 16.4 feet x 16.4 feet. That is quite a difference. Best to not give Square dimensions but give actual Length x Width x Height, then we have something we can work with.

Further the floor-plan matters. Is this a open floor-plan into another room; sort of a combined Kitchen/Living Room or perhaps a combined Living Room/Dining Room? And is that 16x16 both spaces or just one.

What does it have for window? Fireplace? Small closed doors, or large open doors?

These details carry greater weigh in deciding what kind of speaker a given room can accommodate. If this is a completely close 16x6 room (don't know, just using it as an example), then good quality bookshelf might be enough.

In my living room, which is about 16ft x17ft, I have TWO 12" 3-way PLUS TWO floorstanding with TWIN 8" bass drivers each. But, I have an open floor plan this room of 16ft x 17ft opens into a kitchen and entry way that is slightly larger than that. While my functional listening space is small, the available space that the speakers unload into is quite large. So you can see how the specifics of the circumstances can make a difference.

Given the speakers I've listed above, I would personally rather have large speakers played a bit quieter, than have small speaker played a bit louder. The amount of air that you move can have an impact on your perception of the weight of the music.

When designing speaker, if you are using software, the software might ask you to choose between THREE types of speakers.

1.) Most Bass
2.) Flattest Response
3.) Lowest Response

You only get one.


Most Bass will have a big bass peak. This is actually setting the "Q" factor. With a "Q" of 2, you get a really big bass bump. With a "Q" of 1 you get a more modest bass bump. With a "Q" of 0.7 you get the flattest response. With a "Q" of 0.5 the bass starts to roll off much earlier, but rolls off slowly and goes deeper.

So -
Q = 1.0 = Most Bass
Q = 0.7 = Flattest Response
Q = 0.5 = Lowest Response

Q=0.7 is considered ideal for faithful reproduction.

Q=1.0 is about as high as anyone would ever go. Above that, you get into excessive bass.

Q=0.5 is used less often but if you want to go as deep as possible, this is the way to do it, but it comes with some sacrifice. It is the balloon analogy, get it down in one place and it expand in another. Or gain in one place, lose in another.

None of these are wrong, if they give you what you want. Just make sure you REALLY want what you get.

Also, as I have mentioned, perception can be deceiving. You say to someone that my speakers go down to 25hz, and their response is, wow, that must be loud. NO. One has nothing to do with the other, That's like one person saying my banana is green and having the other person respond with "Ford". One has nothing to do with the other. Deep is Deep and Loud is Loud, one is not necessarily the other.

There are many absolutely stunning bookshelf speakers that play music so sweetly it would make you weep. But being small, they don't have great bass numbers. What they do have is crystal clarity and faithful reproduction. (B&W CM5, Dynaudio 160, Kef LS50, and many more).

Myself, I prefer floorstanding. I'm old school, to my ancient mind an 8" speaker is tiny. But then the speakers I grew up with don't exist any more. In today's world an 8" bass driver is consider big.

Ideally, at least in my mind, a good bookshelf speaker should have rated -6dB response BELOW 50hz, though below 40hz would be better.

A good floorstanding should have rated -6dB response BELOW 40hz. Ideally though, 30hz or a bit deeper.

But the key to that statement isn't 40hz or 50hz; it is GOOD speaker. I would rather have a truly stunning speaker with less bass, than have a truly bad speaker with over hyped bass.

As to -3dB response vs -6dB response. -3dB is virtually flat. -6dB is down slightly but still very usable; generally considered the low end of the truly usable range.

That's probably more than you wanted to know, and probably doesn't specifically address you real questions, but it should give you some framework.

Steve/bluwizard

Brilliant post Steve. I actually laughed out loud at these: "Just remember that life and speakers are like squeezing a balloon, you can get it down in one area, but it is going to blow up in another."

^ I'd like that on a t-shirt.

Also: "That's like one person saying my banana is green and having the other person respond with "Ford". One has nothing to do with the other. Deep is Deep and Loud is Loud, one is not necessarily the other. "

^ absolute gold mate haha

 

[aulday]

really good read though, it really is a science of compromise which makes audio so great. There is no one easy way to make 'perfect', just endless combinations of appreciable vibrations

 

[BlueWizard]

The OP is quite correct that bass perception varies greatly from setup to setup and does not seem to correlate with the actual speakers being used. This is simply because the room dominates the problem and the actual speakers are not very important.

Admittedly I'm taking the most extreme interpretation of your statements. The Speaker are important because without them you have nothing. Try taping your speaker wires to you walls and see how they sound.

And while you are right about rooms, one need not get fanatic about it for general listening. In a normal home lounge/living room, good old fashioned soft furnishings and general clutter are about all you need -rugs, carpets, curtains, bookshelves, and just general clutter.

Now, dedicated music rooms and home theaters would certainly need more attention to acoustical details. They typically do not have the general clutter that is found in more old fashioned lounges.

I've said this before, and I will say it again, though I will add a bit more to it. First one doesn't not intentionally design bad speakers and say - "Don't worry, I'll fix it with EQ'. You build the best speaker you can within the limits of your budget and within the limits of your desired result from the speaker. Which brings me to the next and most important point to remember. Room EQ is not the hand of God, it can't work miracles. Room EQ can make a good room better, but it is never going to fix a bad room. Bad is bad, a pig with lipstick is still a pig, A sow's ear purse is still a sow's ear purse. (RE: the old saying, you can't make a silk purse out of a sow's ear.)

But every room is different so what to do?

The solution is to use multiple subs spread around the room and EQ'd in situ. .... Some years ago EQ may have been a problem, but these days with free PC software to do the measurements and EQ readily available through DSP there is simply no reason not to do things this way.

We can debate the issue of multiple subs, though I'm not really the person to debate with. I think it would depend on the purpose of the Subs. I say, not necessary for music. However, if you want knock your out shock waves from movie sound track, multiple subs would certain give you that concussive weight.

Another advantage, in my limited opinion, to Subs, assuming your have reasonably full range speaker in front, is that by setting the AV amp to SMALL, and diverting low-bass from the front speakers, you improve the sound from the Front. I think, in my limited experience, reducing the low-bass demands on the Front, make their job with the remaining frequencies that much easier.

As for myself, while this works well for Home Theater, I'm not a fan of Sub for music systems. Subs are expensive, I would rather put that considerable money into the Front speakers and improve their general sound quality. However, for others who do like Sub for music, more power to you. That's why life offers diversity, so we can each find what pleases us.

This technique makes the speaker type (ported, closed box, dipole, cardioid), Q, resonance, etc. completely irrelevant because you just EQ everything to what is needed in the specific room. The speakers size and power handling are relevant to the extent that they determine how loud (SPL) the system can go. Smaller speakers will only go to say 80 dB, larger ones 100 dB and many 15"s will go to 120 dB. It all depends on what you are looking to achieve.

On this last issue, I'm not so sure I agree. As I've said before there is a limit to what you can do in both Acoustic EQ and Electronic EQ. The design and type of speaker do matter, and they matter to the specific job they are given. It is illogical to use Satellite Bi/Di-poles as front speakers. While the sound would be good, it is somewhat impractical to use a floorstanding speaker as a Center.

Keep in mind, I don't disagree with the general points you made, I just thought there was an overly extreme context applied to the speakers. So, let me modify it this way.

Assuming we are starting with competently designed speakers, appropriate to their purpose, then the critical factor becomes the room. Critically so for dedicated Home Cinema and/or Music Rooms. And I further agree you must deal with the room on TWO fronts. One, you must EQ the room acoustics. That is, you must acoustically treat the room specific to the problems unique to that room. Once you have done that, then you can let Electronic Room EQ refine it further.

But EQ is not the solution to bad speakers or a bad poorly designed room. You need to meet the EQ half-way.

So, in the end, I do agree with what you said, it is the implied context that bothered me; it seemed a bit extreme.

If we start with competently designed, purpose correct speakers, then for a dedicate music room or a dedicated home theater, physical Room EQ as well as electronic Room EQ are critical to getting the best from your considerable investment. A bad room can make the best speaker sound bad.

Just a few thoughts. Though keep in mind I agree with what you said, I just thought the implied context was a bit extreme.

Steve/bluewizard

 

[Pallas]

***We can debate the issue of multiple subs, though I'm not really the person to debate with.*** I'm not a fan of Sub for music systems.

Have you ever actually taken in-situ measurements of stereo loudspeakers in the modal region, say 50-150Hz? Spoiler alert: they suck. All of 'em, in every room. See some collected published in-room measurements supporting that proposition here.

Yes, one can and does eventually get used to low-fidelity reproduction. However, if one cares about reproducing the upper bass with high-fidelity, multiple EQ'ed subs are really the only answer, with a small carve-out for nearfield systems, where a single EQ'ed sub (or heavily EQ'ed mains) are generally fine.

The biggest misconception you have is that multiple subs are to get louder ("concussive") bass. Extra volume displacement to handle organ pedals and such is nice, but the biggest benefit from multiple subs comes above 40-50Hz in most rooms.

 

[BlueWizard]

They may suck in measurements, but I heard many stereo speaker that sound fine and well above fine.

I'm not saying don't use Subs, I'm saying I have no interest in using Subs. For the typical $500 to $1000 of the usual quality Subwoofer, I'll just buy better speakers or sink an extra $1000 into my amp.

At the same time, I certainly don't insist that others do the same.

Steve/bluewizard

 

[Pallas]

They may suck in measurements, but I heard many stereo speaker that sound fine and well above fine.

Lots of people like 7" flush-tweeter 2-ways with polar patterns that look like mushroom clouds, too.

Doesn't make 'em hi-fi, of course. And people used to good speakers will quickly hear the midrange problems.

Get used to a system with clean upper bass, and the flaws of stereo "full range" speakers will be obvious.

 

[AllenB]

@ AllenB,

Hi,

For the 15" I'm surprise it can be used above 400 hz for directivity and good sound stage...and the range above 200 give often a not coherent sound for male singers...most of the time. And what about distorsion and subharmonics above 100 hz to 1200 hz when big movement of the cone of a 15" bass driver ? septical here !

If I make an analogy, maybe I like the mid bass region the Quarter wave box do (but the load is too long for good reactivity no ?)

I intended them to have more narrow directivity, that was a part of the design. These particular drivers were slightly imperfect at the top end so I tried adding a phase plug (which didn't do much). I modified the cone and damped the basket and they came good. I liked them more crossed at 800Hz. I wasn't using steep slopes.

You mention big movement. A large driver is likely to move less than a small driver.

 

[aulday]

I don't mean to thread jack it just seems a very relevant topic. I wondered can some of you cast views on these speakers for use in basic non sound treated rooms:

My PC / home studio speakers rigged to my PC are: http://www.jblpro.com/BackOffice/ProductAttachments/JBL.LSR4326P.v4[1].pdf

I know room mode correction is technically wrong, but it seems to help quieten the room mode in my mix position.

Then downstairs for the living room i have these (currently being refurbished to make as original as possible). I understand they have a time adjusted tweeter, a triple resonator box for the mid/high-bass and a BP enclosure for the subwoofer: http://www.passion-elipson.com/cabasseforum/1303/elipson_1303_11.jpg

^ Sorry I don't have that bit in English

 

[aulday]

My rooms are all closed plan, medium sized for a british house with 1 window each

 

[Eldam]

À big cône used for médium Has bigger movement than a cône only used for medium.
It s not good Because in the same time It act like bass and médium need to come back sooner for details and reactivity. +/_ 2mm us tropical for médium or mid bass...more for bass. The only reason i usé à 15" at 800 hz is à horn...maybe. because i m sûre add à mis woofer.

 

[Eldam]

About the Elipson: you atd correct.

 

[Eldam]

15" interlude

Hi AllenB,

I'm OT here, but that's my thread...and don't mind if others people are OT too
please consider this : http://www.emspeaker.com/fiche_LB12MKII.pdf

This is a 15" maid by a great french specialist . Mr fertin. It klimb to ~ 15k... but double cone and special phase plug ! it does'nt move more than 3 mm. It is said to be fleshy...sure it always the case with 15" used above 150-200 hz . Look at too the dip...maybe a 10" will be flater here ! No miracle it's physic. That's theory, because many people use it with sucess with tubes (it's 16 homs) ... before discover the planars Topics I planed to buy 4 to do a front /rear push/pull dipole in an open box with just a one more tweeter above 10 K for the front speaker !

But now planar is my goal,but in every case, all frequency below 150-200 hz is maybe one of the difficult task according to me in Hi-fi : that's why my question ! You have to marry the bass very good with the mid with not too much tonal difference and with a continue coherent energy (easy on the paper but in reality with room, time alignement and age of the listener...it's another story). after you have to set up the roll off to deal between the bass renforcment and the room which is always shorter than the bass wave ! My understanding is electronic are good to cut somme frequency but not to add them because distorsion and cone break up (?). it's better to add bass speaker and EQ shave ! (But not WAF...not the shaving but the more bass speakers)

One of the solution was maybe to tailor the Q and the 80 to 100 hz, but if I understand the previous post : a bump here give the sensation of a flat curve because of the less sensivity of the ears here (bass area)...

Is there anybody here who maid measures of speakers with fine distributed energy in a room (I don't talk here about tonal and 3D) or is there only one rule to design a speaker : make a flat curve with a 35 hz roll off ?

 

[gedlee]

Admittedly I'm taking the most extreme interpretation of your statements.

So, in the end, I do agree with what you said, it is the implied context that bothered me; it seemed a bit extreme.

Clearly you feel the best response to an extreme comment is to become even more extreme:

The Speaker are important because without them you have nothing. Try taping your speaker wires to you walls and see how they sound.

I always assume a "competent" speaker design - why would anyone deliberately design otherwise? I find it pointless to argue about which junk/broken speaker design is best.

Multiple subs is not for more output, it is for smoother response, hence also necessary for music. Subs need not be expensive and should simply be considered as part of the system to be optimized for both performance and budget.

 

[AllenB]

Eldam, it is a tricky region. Just below the typical 'baffle step', radiation widens. Modes at these lower mid frequencies may be most influenced by a wall or part of the room with patterns that are distinct and specific. A whole room solution based on augmentation may be fiddly. Correction through room placement or speaker design might prove more successful.

Your 15" example is interesting and makes the current point, I think. I'd be interested in seeing some off axis shots before drawing any conclusions. The phase plug appears as if it could be doing something useful but I'm only guessing.

 

[Eldam]

AllenB,

"I'd be interested in seeing some off axis shots" : I think the creator is a good vendor too... I saw nothing else (15° or more)! I'm not sure too that IE measure too ? It's a french tradition : look at PHL Audio, Davis Acoustic, Focal, Audax (better this one for measurement) : hard to have good detailed curve like Seas...

And look at below 200 hz...oups ! Nothing ! In fact it's a big wide band who need certainly a QW box or a classic vented one because I surmise that the form of the cone is verry narrow to help medium range. I don't know where the little cone near the plug phase beginn to start ! i guess the form of the main cone act as a horn because the higher region are maid near the midlle-center (fundamental physic). The second cone is like a tulip than the form of the phase plug follows...

"Correction through room placement or speaker design might prove more successful." I spend a lot of time with placing and for the rest : i'm an absolute beginner !

 

[BlueWizard]

I think you are going to have to explain this phrase -

"...speakers for use in basic non sound treated rooms:"

What is a non-sound treatment room? And how does it apply to the speakers you linked to?

And ultimately, what is your question?

Are asking about Acoustical Treatments in your Mixing room? If so, then we need to know a whole lot more about the room. The dimensions, the general acoustical assessment, the lay out of the room, and what you have done so far.

Steve/bluewizard

 

[BlueWizard]

Clearly you feel the best response to an extreme comment is to become even more extreme:

Precisely, when appropriate. I first noted that I was taking an extreme interpretation so that it would be clear to the reader. Secondly, I was to illustrate to you the context that could be applied to your statements, if the context was taken at its extreme.

I always assume a "competent" speaker design - why would anyone deliberately design otherwise? I find it pointless to argue about which junk/broken speaker design is best.

You made statements that implied the speaker was irrelevant, and that everything can be corrected in EQ, when we all know that is not true. Speaker are relevant, and there are certainly good speaker and there are certainly bad speaker, which once again means that speaker are very relevant.

"The OP is quite correct that bass perception varies greatly from setup to setup and does not seem to correlate with the actual speakers being used. This is simply because the room dominates the problem and the actual speakers are not very important."

"...actual speakers are not very important", I think many people would disagree with you on that. Speaker are very important. First, without them, you don't get any sound. And the quality of the speaker is related to your available budget. If your a starving student with $500/pr at best to spend, then FOUR $1000 Subs are pretty much out of the question. If you are the average kid with at best a 12ft x 12ft bedroom, likely multiple sub are out of the question.

When you say speakers are not very important the implication is that any crap speaker will do, and that it can all be corrected with Room EQ, acoustics, and multiple Subs. We know that is simply not true. But, at its extreme, one could fairly interpret your statements that way; that any crap speaker will do since speakers are not very important, when we all know they are vitally important.

Keep in mind, in concept I agree with you, but there are whole lot of realistic and practical factors that you are ignoring.

Long before I would ever buy FOUR $1000 Subwoofer, I would by one pair of Floorstanding speakers and add $4000 more the front speaker budget. It is about priorities and best expenditure of limited budget. There are too many things at a higher priority than multiple expensive Subs.

However, once you have everything else into place, and have balanced the system to the extent possible, and your rich uncle dies and leaves you a fortune, only then does it make sense to consider multiple subs.

In theory, you are probably right, but in practice, I don't think multiple Subs is anyone's priority. Getting a good amp and a good set of speaker, I think, tops everyone's list.

Multiple subs is not for more output, it is for smoother response, hence also necessary for music. Subs need not be expensive and should simply be considered as part of the system to be optimized for both performance and budget.

In a Stereo system with decent front speakers, Subs are unnecessary. The only time to consider them, in my opinion, is when your front speakers are small and you want deeper bass. But, I still say spending that money on better front speakers will yield better results in overall sound quality. You are concerned with improving one small range of sound, I'm considered with improving the full spectrum of sound.

Now, certainly I'm in no position to forbid anyone anything. I'm sure there are tons of Bass Heads out there that insist on a Subwoofer no matter what their front speaker are. Fine, their life, their money.

And if you insist on multiple Subs, fine, your life, your money. Just don't inside that others conform to your views.

Certainly express your view, you might sway others to your way of thinking. Just don't get the idea that your view came down from on high in the shape of a lightening bolt. You have an opinion, perhaps a highly qualified opinion, and perhaps you have the income to back up that opinion. But for most users, that absolute top critical priority is a good amp and the best front speakers you can afford. From that point, then we have room to work with extras for as long as the cash holds out.

Admittedly, just one man's opinion.

Steve/bluewizard

 

[BlueWizard]

I think you are going to have to explain this phrase -

"...speakers for use in basic non sound treated rooms:"

What is a non-sound treatment room? ...

EDITED:

Actually I just got it. I took NON sound treated room to mean, treated room in which there was no sound. What you really meant was a Sound Room that had not yet been treated.

But you still didn't really ask a question. Nor did you provide us with critical details about your given room.

I think at its most basic, you want the mixing console in the center of a wall, so you get symmetrical response.

Second, you want your speakers at close to ear level and symmetrically placed. Also the speakers placed at an appropriate distance from the wall behind the speaker. Though for typical Near Field Monitors, this distance in not that large.

Third, you want to deal with the "Point of First Reflection" to the sides of the listener.

Forth, you probably want to do something about reflections off the far wall opposite the mixing console. Probably a blend of absorption and diffusion.

Depending on other factors, you might want to deal with first reflection point on the ceiling.

Steve/bluewizard